The objective of this Phase I proposal is to determine the scientific, technical, and commercial merit and feasibility of an integrated commercial treatment planning and dosimetry system (RTDS) for radionuclide therapy and radionuclide imaging, especially for radioimmunotherapy (AlT). In clinical and experimental RIT, knowledge of the absorbed dose in normal organs and tumors is essential in gaining an understanding of normal tissue toxicity and tumor dose response. This project will lead to a user-friendly software program allowing physicist/physicians to perform dosimetry analysis during AlT treatment. The software package will be integrated into the CMS FOCUS 3D radiation treatment planning system, allowing the delineation of organs and tumors, the co-registration of CT and nuclear medicine image sets, and the estimation and visualization of absorbed dose in critical tissues. User will have the option to purchase the RTDS module to perform treatment planning and dosimetry calculation for patients receiving radionuclide imaging and/or therapy. It will be the first commercially available treatment planning system of this kind and will be fully supported by CMS, inc. More importantly, this project will provide a general framework to perform AlT dosimetry and the opportunity to standardize the dosimetry technique and methodology used in RIT. PROPOSED COMMERCIAL APPLICATIONS: This project will lead to a user-friendly software program allowing physicist/physicians to perform dosimetry analysis during radionuclide therapy and radionuclide imaging procedures. It will be the first commercially available and fully supported system. It will be widely used by hospitals and medical centers that perform radionuclide therapy and radionuclide imaging, especially radioimmunotherapy (RIT) treatment.